Since the introduction of personal computers, the computer keyboard has become substantially standardized, with a large number of keys. These keys include the ones previously associated with electric typewriters, along with additional function keys and special keys such as control keys, alternate keys, number lock, insert, home, end, cursor direction keys, etc. The result is a relatively large keyboard, typically occupying an area eight or nine inches side and seventeen to nineteen inches long. For desk-top personal computers (PCs), a keyboard of this size is no problem; and the keys are arranged in generally standard patterns. Whenever a key is operated, a signal is supplied from the keyboard to a keyboard microprocessor for effecting the desired operation. For some keys, such as "shift (SHFT), control (CTRL), and alternate (ALT), a combination of the operation of this key with other keys on the keyboard is used to effect the desired operation in the computer. The standard PC keyboard, which has been widely adopted, is based on the IBM.RTM. PC/AT scan code system.
Portable and lap-top personal computers (PCs) now are becoming increasingly popular. One of the primary advantages of such computers is their small size and weight, which permits them easily to be carried in briefcases or separately, if desired. These portable personal computers employ flat screen displays and, in efforts to reduce their sizes, employ keyboards with substantially fewer keys than are found in a standard desk-top personal computer system.
To provide all of the outputs to the computer which are obtainable from the larger desk-top keyboards described above, portable and lap-top PCs utilize a matrix keyboard arrangement. As portable or lap-top keyboards get smaller, single keys become a composite of several keys found on standard PC/AT keyboards. Depending upon the shift state of the keyboard, these keys dynamically generate different scan codes. This economizes the number of keys required and permits a reduction in size of the keyboard used with such computers.
Unfortunately, matrix keyboards used in personal computers do not currently have a standardized design. As a consequence, when these keyboards are used in conjunction with the programs, microprocessors and other circuitry designed for personal computers, a translation of the matrix keyboard coordinates into the standardized scan codes or keyboard signals for IBM.RTM. PC/AT keyboards must be effected. For different keyboards this required different software and scan code translation tables to be designed into the portable personal computer itself. In the past, a combination of in-line code design making and table translation has been employed to do this. No universal system, capable of operation with matrix keyboards having different assignments for various keys, has existed.
It is desirable to provide a system and method for a scan code generation system used with matrix keyboards which does not require new keyboard support software and hardware for each different matrix keyboard.